While the HVAC trade as we know it today is defined as mechanical systems that help heat, ventilate, and cool (air conditioning) buildings, the modern HVAC system stems from centuries of innovation. Find out how humans first started heating and cooling their buildings, and how HVAC has evolved into an advanced mechanical trade.
While the timeframe is disputed, humans mastered fire at their earliest existence, with clear evidence dating back to 125,000 years ago. It was, and remains, humanity’s primary source of heat, whether it be through lighting a fire in a cave or igniting a modern gas-powered heating system.
Evidence points to ancient Greece as responsible for first using the heat-power of fire to create a central heating system. They built flues (a duct or pipe) underneath buildings that spread the heat created by fire throughout the buildings. The Roman Empire advanced the Greeks’ heating system work by building furnaces, which magnified the heat created by fire, and transferring it through pipes underneath floors and inside walls.
As with the Roman Empire’s heavy influence on the history of plumbing, the Empire’s fall caused a delay in the innovation of the history of heating. During the medieval era, buildings were heated mainly by fireplaces, with some highly efficient heating systems powered by furnaces still in existence. Small modifications were made to make the primitive fireplace more efficient, according to Master.ca, including reducing the size and installing metal plates inside the hood to keep hot air in and cold air out.
In the 1700s, hot air was used to centrally heat buildings through pipes in the walls. However, radiators soon began to take over the heating trade, starting with steam radiators and evolving into hot water radiators. In the 1900s, homes began to receive heat in every room rather than only one or two heat-equipped rooms. Boilers that powered radiator heating systems made this possible around the world.
Now, we have heating systems that can also be powered by electricity, solar energy, or even local geothermal heat.
As fire has remained the primary source of heating, water has been humanity’s primary source of cooling. When water evaporates, it has a cooling effect, which was discovered by ancient Egyptians. They hung wet reeds in windows, allowing the air that blew into the room to cause water evaporation and, thus, inside air cooling.
Other ancient societies developed cooling systems, including the ancient Romans whose aqueducts transferred cool water through walls. China saw the invention of the water-powered fan as early as the 2nd century.
Mechanical refrigeration, Energy.gov cites, began in the mid-1800s with the invention of an ice-making machine. Motivated by the idea that cool air could benefit sick patients, American Dr. John Gorrie invented a machine that powered a compressor by steam, wind, water, or horse and successfully made ice. His invention, which was an important development in the history of refrigeration, was never adopted publicly.
Willis Carrier is credited with inventing the first modern air conditioner in 1902. While searching for a way to control humidity, Carrier designed a cooling and heating machine, which could dehumidify and humidify air.
Cooling systems began to be widely embraced by the public in the 1920s when public movie theaters adopted the distribution of cold air through floor and ceiling vents. While these systems were widely implemented in public spaces, they were too large to be added to individual homes until the 1930s when General Electric optimized a “self-contained room cooler,” according to Energy.gov. This quickly led to the creation of the window air conditioning unit.
By the 1960s and 1970s, central cooling had been improved and downsized to be added to most homes, leading to a drastic rise in energy usage. Energy conservation and efficiency has since been an important part of the HVAC trade, affecting the way recent HVAC system history has developed.
While the history of heating and the history of refrigeration and air conditioning developed separately, the heating and cooling fields have merged as homes and buildings are often able to share one system for both purposes. And as humidity can lead to warmth, and dryness can lead to coolness, the field requires a good understanding of how water can affect temperature. Those in the modern HVAC industry can focus on some areas in the field including:
Heating and cooling has become a central part of modern society, allowing us to achieve optimal comfort in our buildings. You can learn more about how society has pursued building comfort in this article about the history of construction.
Now that you know some HVAC history, consider pursuing the trade. Learn more about the Air Conditioning, Refrigeration and Appliance/Controls program at Apex.
*Apex Technical School and its instructors are licensed by the New York State Education Department.
Disclaimer: Apex Technical School provides training for entry-level jobs. Not everything you may read about the industry is covered in our training programs.